Search

This article derives from the research project “Analysis of the efficiency of electrocoagulation with aluminum electrodes for the reduction of turbidity and chemical oxygen demand (COD) in wastewater from fur cleaning process in the municipality of Villapinzón,” developed at Universidad Libre, Bogotá, in 2019. These wastewaters have high concentrations of polluting substances that are discharged and affect effluents. Therefore, this study seeks to evaluate a laboratory-scale electrocoagulation system in order to remove turbidity and COD by means of tests carried out in discontinuous mode for periods of 45 minutes. With variations in the number of electrodes (2, 4 and 6; flat and perforated), and an applied current of 12 A and 10 V, the maximum removal of turbidity, sulfides and COD reached values of 99.77 and 74.1% respectively, when 4 flat electrodes were used. For turbidity, the use of perforated electrodes allowed obtaining removal values of 98% (with 2 electrodes). This technique also allows to eliminate sulfides, using 4 and 6 electrodes, thus achieving removal figures of 45.86 and 48.21%, respectively. Findings of this study conclude that the adequate number of electrodes for the process is 4, and that increasing the number of electrodes reduces the current density, increases the contact area, and favors the dissolution of aluminum excess. [ABSTRACT FROM AUTHOR]

The interaction of biostimulant species of Trichoderma may have benefits to increase the production of metabolites involved in promoting plant growth; combining two organisms with a higher degree of antagonism could enhance their plant growth promoter effects. The objective of this study was to select in vitro native species of Trichoderma in a dual cultivation, and to evaluate their growth-promoting effect on Capsicum chinense. The selection of isolates in vitro was done by dual confrontations with the following characteristics: proportional growth of both isolates in the Petri dish; presence of mycelial barrier; and colour of the culture medium. The selected confrontations and their individual isolates were evaluated in plants of C. chinense cv. Mayapan. Also, two controls without fungal inoculation were assessed, one as control with 100% of the chemical fertilization (250N-200P-300K) recommended for the culture; and the second as control at 50%, with half of the indicated fertilization. Three applications of suspensions of 106 conidia mL-1 were made in the seedbed stage and another three during the growth of the culture. The effect of the treatments was evaluated through plant growth and crop production 145 days after sowing. The interaction of Trichoderma virens (Th05-02)/Trichoderma koningiopsis (Th41-11) was equal (p>0.05) to the 100% fertilized control in the variables evaluated. In addition, increases of 14.53% were recorded in plant height, 11.20% in stem diameter, 28.54% in foliar dry biomass, 12.97% in dry root biomass, 33.13% in a number of fruits, and 25.77% in the weight of fruits, compared to the control with 50% chemical fertilization. The species interaction of T. virens (Th05-02)/T. koningiopsis (Th41-11) exerted a plant growth promoting effect with 50% reduction in the recommended chemical fertilization for habanero pepper cultivation. [ABSTRACT FROM AUTHOR]

The purpose of the investigation was the use of petcoke as an additive to reduce the nickel and cobalt present in a lateritic mineral. Following a unifactorial design, we experimented with a variable: content of petcoke as an additive with nine levels (1, 2, 3, 4, 5, 6, 8, 10 and 12 %). The chemical reduction was carried out in a bottle oven (Selas oven) at a temperature of 750 oC. The best extraction results are achieved with the increase in the content of petcoke used as additive, obtaining for a 12 % extractions of nickel and cobalt of 81,4 and 64,3 % respectively. A high correlation of this variable was obtained with the nickel and cobalt extractions; 86,2 and 95,9 % respectively [ABSTRACT FROM AUTHOR]

In most laboratories dengue antibodies are measured by hemagglutination inhibition (HI), complement fixation (CF), or enzyme-linked immunoassay (ELISA) tests adapted to micromethods. They do not reliably identify the infecting serotype. This paper proposes a description of the modified semi-micro plaque reduction neutralization test used successfully. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work the distillation by pressure reduction was evaluated through the HYSYS v3.2 process simulator. Due to the lack of data in the consulted bibliography to perform the simulation, the STATGRAPHICS Centurion XVI software was used to obtain a response surface that would define optimal operating conditions. The property package selected to work was based on the Margules model. An anhydrous ethanol molar composition of 0.9917 was obtained. Temperature profiles were analyzed as well as liquid and vapor molar flows and dehydration column composition profiles. The influence of operating parameters on the efficiency of simulated technology was determined by analyzing one case study. According to economic evaluation, the implementation of this technology is not economically profitable; taking into account current prices and costs mostly due to high energy consumption and construction costs of the tower. This result contributes to the pursuit of other profitable technologies from the economic point of view. [ABSTRACT FROM AUTHOR]

The aim of this work was to characterize the natural clinoptilolite from Tasajeras deposit, Cuba, modified by hydrothermal ion-exchange with solutions of iron (II) sulfate and iron (III) nitrate in acid medium. Besides this, its catalytic activity to reduce nitrogen monoxide with carbon monoxide/propene in the presence of oxygen was evaluated. The characterization was performed by Mössbauer and UV-Vis diffuse reflectance spectroscopies and adsorption measurements. The obtained results lead to conclude that in exchanged samples, incorporated divalent and trivalent irons are found in octahedral coordination. Both irons should be mainly in cationic extra-framework positions inside clinoptilolite channels as charge compensating cations, and also as iron oxy-hydroxides resulting from limited hydrolysis of these cations. The iron (III) exchanged samples has a larger amount of iron oxy-hydroxides agglomerates. The iron (II) exchanged samples have additionally iron (II) sulfate adsorbed. The catalytic activity in the nitrogen monoxide reduction is higher in the exchanged zeolites than starting. Among all samples, those exchanged of iron (II) has the higher catalytic activity. This lead to outline that, main catalytically active centers are associated with divalent iron. [ABSTRACT FROM AUTHOR]

The reduction of ferruginous lateritic mines under non-isothermal conditions in Nicaro was analyzed using pure carbon, anthracite carbon and carbon fine coke as reducing agents. A Derivatrografh Q-1500D machine which operates at heating temperatures of up to 1 200 °C was used for the thermogravimetric analysis. The use of pure carbon resulted in a variation of the apparent activation energy from 10 kJ/mol to 70 kJ/mol, indicating that the process is controlled by a chemical reaction. [ABSTRACT FROM AUTHOR]

Copyright of Superficies y Vacío is the property of Sociedad Mexicana de Ciencia y Tecnologia de Superficies y Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The contextualization of chemistry is of great importance to our society as it allows to bring this science to students of secondary education thus facilitating the learning process, so that students can identify and explain the phenomena that occur around. As a way to improve student learning, driven redox processes are contextualized through the process of corrosion of metals, which can place them in real contexts, for which there were two experiences, one on corrosion reactions that occur over an extended time due to constant contact of the coins one hundred Chilean pesos, the old and current human sweat by verifying which of the two alloys are most affected. The other experience is to determine qualitatively the degree of corrosion experienced by coins of the same value mentioned above, through two media, a dry and moist soil, respectively. Both activities were used with chemical reagents readily available. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of the investigation is to obtain a material from "René Ramos Latour" nickel plant's solid wastes with steel properties. To meet the objective, solid wastes were subjected to magnetic concentration and agglomeration by pelletization, using bentonite as an agglutinant. The resulting pellets of 14 and 18 mm diameters were able to withstand compression in green of 9,71 and 6,98 kg respectively. It is demonstrated that it is possible to obtain 76 % metallization and 80,42 % reduction after carrying out reduction tests at temperatures of 1 265 °C in the furnace and cooling in inert atmosphere. [ABSTRACT FROM AUTHOR]

A mathematical modelling of the reduction process for the ferronickel production was completed. Based on the equations of mass and energy balance, a system of equations forming a dynamic mathematical model is presented as well as the scientific foundations upon which they were obtained. The main oxides and elements minerals of construction of the furnace walls and of the reducing gases were considered for the transformation of the mass and energy balance equations. A system of first order differential equations, complemented with other algebraic equations establishing the relation between coefficients and physical parameters, was obtained. [ABSTRACT FROM AUTHOR]

Copyright of FABICIB: Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral is the property of Universidad Nacional del Litoral and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents an optimal power flow model using the gradient method for the reduction of losses in power systems. The algorithm allows adjusting a set of control variables to find an operation point that minimizes active power losses. The method is based on the power flow solution by Newton's method. Limits on idependent variables are handled using penalty functions. The algorithm performance is tested using two different approaches to calculate the step size along the feasible direction: a constant step size and a variable step size using the parable adjustment method. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this work it was carried out a systematizing abaut the different factors influencing in the magnesium leaching in ammonio amoniacal carbonate liquors. There were related the insoluble complex compounds formed, causing of inlays. The reduction temperature effect and the mineral composition on the formation of free or amorphous magnesium were analyzed. For simple lineal regression a directly proportional relationship was obtained among the increment of the magnesium in the fed mineral and the free or amorphous magnesium formed in the reduced mineral to oneself temperature of reduction of 750°C, with a correlation coefficient of 0,9699 and standard error, 0,18. [ABSTRACT FROM AUTHOR]

The effect of the concentration and the size of particles of the solid waste slurries in the reduction of SO2 in the combustion gases was studied in the present work. The reduction obtained was between 64-85 % of SO2 in the first 5 min with an increased in time. The pH profile was determined on time resulting a decrease of it. [ABSTRACT FROM AUTHOR]

In the present work it was extended to 27 kinetic models the analytical expressions of solid sate kinetics for the Temperature Programmed Reduction technique that allowed to wide the field of investigations for to establish the influence of heating rate on the maximum of reduction rate or that is the same, to use the generalized Kissinger equation as a method of kinetics investigation. It are given the expressions for the f(α) and g(α) functions previously verified its agree and also it are given the respective functions depending of temperature at which reduction rate is maximum. The use of the method it is presented in the kinetic investigation of non stechiometric nickel oxides. [ABSTRACT FROM AUTHOR]

In this paper a quantitative physical characterization of the chromite concentrated with refractory characteristic belonging to the deposit Merceditas is presented, using for it technicals of infrared and Mössbauer spectroscopies, X-ray difractometry, chemical and grain size analysis. It settles down that the concentrate is constituted by the phases mineralogical well-known as chromopicotite, antigorite and chlorite, being determined its respective cristalo-chemical formula. By means of the techniques of thermal analysis (DTA, TG and DTG) the thermal behavior of a mixture of chromite concentrated and aluminum is studied with the purpose to valuing the possibilities of the products of the reduction like component of saturating mixtures for the thermodifusives surfaces of chromium and silicon in steels. [ABSTRACT FROM AUTHOR]

It was established that for some of the elements studied, are presented differences in the values calculated for the different types of flame, what demonstrates the necessity of using the real diffusion coefficients in the estimation of parameters that are used in the evaluation of the mecanisms of atomization. [ABSTRACT FROM AUTHOR]